Roof-top devices that are fitted as an accessory to the roof of a motor vehicle and that increase the stowage volume in addition to the vehicle's normal luggage compartment are known in the art. Conventional roof-top devices are generally attached to a roof rack system or are connected directly with the vehicle roof by attachment feet, claws, or the like. As a result, conventional roof-top devices are subject to a disadvantage in that the device may only be used in conjunction with a roof rack system or have complicated attachment devices to connect the roof-top device to the vehicle roof to ensure reliable attachment while the vehicle is being driven.